OTTAWA - The Harper government is being lampooned on Twitter for invoking the name of Adolf Hitler to beat up on the NDP in the House of Commons.

"It's always nice when PM of your country can get "Hitler" trending again.. sighs," someone using the user name @cdnpoli tweeted.

Prime Minister Stephen Harper first mentioned the name of the infamous Nazi dictator on Thursday during the daily question period.

Fielding questions from the NDP about how long Canadian troops would stay in Afghanistan, Harper accused the official Opposition of being reluctant to support the decision to declare war on Germany in 1939.

Foreign Affairs Minister John Baird said much the same thing on Friday.

The Hitler references triggered a flood of mirth on Twitter, with jokesters citing Star Wars, hockey and even dental humour.

"The #NDP didn't even support the fight against the Death Star," @danspeerin tweeted.

"The NDP shamefully stood by in the fight against plaque and gingivitis," added @canadiancynic.

@jagmeetNDP claimed the NDP "is the reason the Leafs haven't won the Stanley Cup since 1967."

Dan Harris, a Toronto New Democrat MP, got in on the act Friday in the Commons, poking fun at the Conservatives by reading several of the hundreds of tweets that have poured in.

"In the spirit of co-operation I'd like to offer the prime minister some great suggestions for next week's attacks on the NDP," he said.

Harris also acknowledged that the NDP wasn't actually founded until more than 20 years after the start of the Second World War, and that he was referring to its predecessor, the Cooperative Commonwealth Federation, or CCF.

The Prime Minister's Office was unrepentent about Harper's comment.

"That the CCF leader opposed war against Hitler's Germany in 1939? It's a fact. Maybe some people don't like history," said Harper spokesman Andrew MacDougall in an email.